Hyperhomocysteinemia is reportedly a prevalent, independent and graded risk factor for all major forms of vascular disease and thrombosis, and more recently it has been associated with neural tube defects and Alzheimer's disease. Betaine-homocysteine methyltransferase (BHMT) is proposed to have a major role in the regulation of blood homocysteine (Hey) levels. The physical and mechanistic properties of BHMT and the extent to which variation at the BHMT locus contributes to the incidence of hyperhomocysteinemia represent major gaps in our understanding of Hey metabolism in both normal and pathological states. The long-term goal of the U.S.Principal Investigator's parent grant is to elucidate the role BHMT has in regulating Hey levels in humans. The objective of this FIRCA application is to design, synthesize and characterize new BHMT inhibitors that mimic the hypothetical transition-state binding of substrates to the enzyme's active site. Two classes of compounds are planned: (i) sulfanyl moiety-containing compounds (type A) and (ii) phosphonate-containing compounds substituted by nitrogen or sulfur containing moieties (type B). The most promising inhibitors will be used in pharmacological experiments for studying the role of BHMT in vivo. This research will be done primarily in Prague at the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic in collaboration with Dr. Jiri Jiracek as an extension of NIH grant # R01DK52501.